In January 1969, U.S. Pat. Nos. 3,421,692; 3,421,699 and 3,425,058 issued to Robert S. Babington, the present applicant, and his co-inventors. These patents disclose a type of liquid atomization apparatus which is particularly useful in liquid fuel burners. The principle involved in the apparatus, now frequently referred to as the "Babington principle," is that of preparing a liquid for atomization by causing it to spread out in a free-flowing thin film over the exterior surface of a plenum having an exterior wall which defines the atomizer bulb and contains at least one aperture. When gas is introduced into the plenum, it escapes through the aperture and thereby creates a very uniform spray of small liquid particles. By varying the number of apertures, the configuration of the apertures, the shape and spray characteristics of the surface, the velocity and amount of liquid supplied to the surface, and by controlling the gas pressure within the plenum, the quantity and quality of the resultant spray can be adjusted as desired to suit a particular burner application. Various arrangements of such atomization apparatus have been disclosed in other U.S. patents issued to the present applicant, namely U.S. Pat. Nos. 3,751,210; 3,864,326; 4,155,700; and 4,298,338. The disclosures of the patents mentioned in this paragraph are specifically incorporated by reference into this application.
So that liquid fuel burners and liquid atomizers constructed in accordance with the Babington principle will have the widest possible range of applications, it has been found desirable to provide the maximum possible variation in the volumetric flow rate of the atomized fuel or other liquid between the lowest and the highest flow rates required. For example, flow rates as low as 0.3785 liter (0.1 gallon) per hour may be required for some applications and as high as 3.785 liters (1.0 gallon) per hour may be required for others.
Once the particular geometry for a given atomization apparatus has been selected, however, changes in the flow rate of the atomized liquid must be made primarily by adjusting the flow rate of liquid onto the atomizer bulb. For the lowest flow rates desired, the liquid film thickness at the aperture preferably would be the thinnest achievable while still maintaining a continuous film over the exterior surface of the atomizer bulb. On the other hand, to provide higher flow rates of the atomized liquid, it is necessary to increase the thickness of the film at the aperture without increasing it so much that undesirably large liquid particles are formed. In the prior art apparatuses, a single liquid feed tube has been positioned above each atomizer bulb a distance of approximately 3.175 to 9.53 mm (0.125 to 0.375 inch) so that a variable flow rate of atomized liquid from about 0.757 to 2.27 liters (0.2 to 0.6 gallons) per hour has been achievable. Various applications have remained, however, in which flow rates above and below this range have been desired but have not been reliably achievable.